Ferguson says their two-leg tie against José Mourinho's team, starting in the Bernabéu on Wednesday, will be "the acid test" for the squad he has been putting together since Barcelona took them apart in the final two years ago.

He has won only three of his 14 encounters with Mourinho and will have to devise a plan to stop Cristiano Ronaldo, a player Ferguson believes has legitimate credentials to be recognised as the greatest footballer in Madrid's history.

"Ronaldo is the one to worry about," United's manager said. "His speed, his goals, he plays every week, never asks for a rest. These qualities are exceptional. He was a young man when he left us, but he has flourished and is a better player now."

However, Ferguson also praised his own team, arguing they were in danger of being underrated. He made it clear that he believes they deserve greater recognition bearing in mind their points total at the top of the Premier League.

"People say that this is not as good as the teams of the past but sometimes there are foggy recollections of teams of the past," he said. "I do it myself. The fact is this team doesn't know when it's beaten, which is a good asset, and we have some quality players.

"The acid test is tomorrow, no doubt about that, and we have to get through to win this competition, no doubt. But there's a great spirit about this team and they deserve recognition. It's unfortunate we're meeting this early. I wish it had been at Wembley."

Ferguson said he was encouraged by the form of Robin van Persie, who had been "nothing short of sensational since he came, a breath of fresh air, good with the youngsters and 23 goals tells you everything". Yet the United manager also spoke at length about Wayne Rooney's possible impact on the match and made it clear that he still gave David de Gea his full support despite the scrutiny on his goalkeeper.

"It's like a kid taking his first steps forwards. He wobbles, gets up, wobbles, gets up again and eventually he walks. The boy is walking now."

Ferguson is promising it will not be a United performance lacking adventure. "If you ask me about Real Madrid I'd have to say they are one of the best counterattacking teams there are. Their speed from penalty box to penalty box is very good and we are extremely aware of that. But the intention for Manchester United is always to win and always to score."

Madrid's attempts to disrupt United came on the front page of Marca, with Wayne Rooney described as 'El Coco', after one of the monsters from Sesame Street. Inside the newspaper described him as a "freckled demon" and a "football player and a hooligan all rolled into one".

Mourinho, whose press conference underlined his worsening relationship with the Spanish media, pointed out that "if I can support Rooney I have been called, week after week, worse than that".

Ferguson brushed off the insults. "I'm not interested in what a Madrid paper says. Rooney can't speak Spanish, can he? So he's all right."

Ferguson has left Paul Scholes in Manchester because the midfielder is suffering from a knee injury that is increasingly causing concern for United's medical staff. Apart from Darren Fletcher, however, United have no other issues.

"I think it is a good time for us," Ferguson said. "We have a fantastic lead in the Premier League and have everyone fit when, to come to this part of season, you generally have two or three more injured. We don't have that, so it is a good bonus for us."

Mourinho had earlier made it clear he wanted to return to England once his time at Madrid is brought to a close but said he could not imagine replacing Ferguson at Old Trafford because he envisaged him working until he was 90.

Ferguson responded by saying he could imagine Mourinho taking over from him one day as the most successful manager in the business. "He is a young man at 50 years of age. He has 20 years to catch up me and it is quite possible he could catch me."

As for himself, Ferguson said: "It's against the law to force retirement so I've no worries. "I won't be working until 90, believe me. But I enjoy my work and while my health is there I will carry on."